Finely-divided vat dyestuffs and process of making same.



ADOLF STEINDORFF AND ROBERT WELDE, OF HOOHST-ON-THEMAIN, GERMANY,

ASSIG-NORS TO FARBWERKE VOBM. MEISTER LUOIUS &

BR'O'NING, OF HOGHST- ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY.

FINELY-DIVIDED VAT DYESTUFFS AND PROCESS OF MAKING SAME.

No Drawing.

To all whom it may concern:

Be it known that we, AnoLF Srnmnonrr, Ph. D., chemist, and ROBERTW'ELDE, Ph. D., chemist, citizens of the Empire of Germany, residing atHochst-on-the-Main, Germany, have invented certain new and usefulImprovements in Finely-Divided Vat Dyestuffs and Processes of MakingSame, of which the following is a specification.

We have found that by treating vat-dyestuffs derived fromthedihydro-1.2.2'1'- anthraquinonazin series, for instance the commercialindanthrene RS of the formula /\(coj/\( o 3/ (lie and indanthrene GC,etc., with more or less highly-concentrated sulfuric acid, the quantityof which should be so moderate as to be insufficient for the solution ofthe dyestuffs at ordinary temperature, it is possible to convert theindanthrenes, which are generally of a very coarse consistence (such forinstance as the indanthrene as obtained directlyfrom the fusion or afterbeing purified) into an extremely finely-subdivided form suitable forvarious purposes, particularly for the preparation of pigment-dyes whichpossess a greater covering power than the commercial indanthrenes andthe product obtain able by treatment with glucose and alkali; when usingcrude indanthrene it may be purified during this operation.

In the following description we comprise under the term sulfuric acid:sulfuric acids of various strength, viz: fuming sulfuric acid as Well asmonohydrate, concentrated sulfuric acid and the various stronglydilutedsulfuric acids.

When the indanthrene stirred in the cold with moderate quantities ofhighly concentrated sulfuric acid, that is to say, with a quantityinsufficient to dissolve the indanthrene in the cold, for instance withfive times the quantity of mono- Specification of Letters Patent.

is mixed and Patented July 13, 1915.

Application filed April 9, 1914. Serial No. 830,748.

hydrate, said indanthrene can be transformed into a solid sulfate whichseparates from the mass. The thus obtained sulfate- Inagma may bedissociated by adding water whereby a finely-divided indanthrenedyestulf is obtained. The indanthrene, thus converted, can be used forvarious technical purposes according to the manner in which it has beenprepared, that is to say, according to the working conditions chosen(for instance lower or higher temperature, lower or higherconcentrations, etc.) a. e. accordingly as the sulfate has separated ina more finely or in a coarser crystalline form, or in an amorphous form,the latter being obtained When the operation is performed quickly and ata low temperature.

hen the indanthrene is mixed and stirred, for instance at about 0 or 5C. with five times the quantity of monohydrate or sulfuric acid of 66Be., it will be completely transformed with change of the color; thus ayellowish-green magma is obtained consisting of the separatedindahthrene-sulfate. If this sulfate-magma is introduced into icewater,the blue pseudomorphous indanthrene corresponding to theindanthrene-sulfate is obtained, its formation being due, as we havefound, to a pseudomorphosis of crystals. This pseudomorphous indanthreneexhibits, when seen through a microscope, the same form of the minuteindividual particles as the sulfate. The sulfates obtained generallyshow crys tals Which are the smaller (being sometimes even amorphous)the quicker the operation for preparing them is performed and the lowerthe temperature employed. Simultaneously with the above operation theindanthrene can be purified in the following simple and easy manner:Impure indanthrene, for instance indanthrene RS powder, crudeindanthrene, etc., is treated with concentrated sulfuric acid ormonohydrate, the quantity of which should be so moderate as to beinsufficient for the solution of the dyestuffs at ordinary temperature.The yellowish-green magma of indanthrene sulfate thus obtained isfiltered off and the indanthrene-sulfate remaining on the filter isdissociated With ice-water; thus an indanthrene is produced which notonly shows a good division, but which also gives cleaner and more evenprints than the parent indanthrene. In connection with the foregoingprocedure we have furthermore found that by mixing not entirely pureindanthrene, for instance commercial indanthrene RS, and particularlycrude-indanthrene, with sulfuric acid of lower concentration, forinstance with one of 60 B., a bluish-green magma is obtained, and that,although this magma turns yellowish-green, there is only a partialformation of indanthrene sulfate, the substances accompanying theindanthrene, particularly fiavanthrene, dissolving to a yellowish-brownsolution while pure indanthrene remains.

On the basis of the foregoing observations there can also be carried outa process for purifying indanthrene which may at the same time beutilized for obtaining indanthrene in the desired subdivided condition,that is to say, either in fine or coarse crystals, or in an amorphouscolloid-like form, the procedure being as follows: Crude indanthrene istreated with concentrated sulfuric acid to transform it into theyellowishgreen indanthrene sulfate which separates; to the magma thusobtained is then added a small quantity of water so as to obtain an acidof a lower concentration viz. of about -80 per cent. strength, whereuponthe indanthrene remains separated in the mass, partly as such and partlyin the form of a sulfate, while the impurities still become dissolved.Finally the mass is separated from the mother-liquor by filtration. Theremaining indanthrene, i. e. the product which is partly composed ofindanthrene and partly of indanthrene-sulfateaccording to the grades ofthe dilution usedis dissociated with ice-water and washed.

Instead of treating first with concentrated sulfuric acid and thendiluting to a sulfuric acid of 60 or 75 per cent. strength andfiltering, the indanthrene may be treated directly with sulfuric aciddiluted to a strength of about 60-80 per cent., and then freed from theacid by washing. By thus treating coarsely divided indanthrene-dyestuffs(no matter whether they are coarsely amorphous or coarsely crystallinei. 6. conglomerated), for instance by treating commercial indanthrene BSor GC powder, or indanthrene obtained from the solution after fusion,the said dyestuffs are converted into very finely dividedindanthrenedyes; for we have found that coarsely amorphousindanthrene,-as it is obtainable by pouring a solution of indanthrene ina large quantity of concentrated sulfuric acid into water andfiltering,-can be transformed into finely divided indanthrene consistingof minute crystals, by treatment with sulfuric acid of low concentration(for instance one of 58B.) so that there is substantially no formationof indanthrene-sulfate. The dyestuffs thus obtained are of a very goodyield as pigment-dyes as compared with the already known commercialbrands. The ordinary dibromo-indanthrene heretofore known did not existin the form of crystalline particles.

'We have furthermore found that, even when using an acid of a stilllower strength and working at a higher temperature, for instance at100120 0., all the indanthrene dyestuffs, z. 6. those which show nocrystalline but an amorphous structure, and also those in which a moreor less coarse structure is discernible, can be transformed from thecoarse amorphous or crystalline initial powderform into a magma of veryfine, uniform crystalline needles. The working up of this magma is alsoin this case preferably effected by diluting with ice and filtering thedyestuif; and if an impure, crude indanthrene is used for thetransformation, it is advantageous to filter the transformed magmadirectly, or, if desired, after further dilution with sulfuric acid,whereby the impurities will be retained in the sulfuric acid lye, theresidue being then washed with water.

'The following examples will illustrate our invention, the parts beingby weight.

Example I: 100 parts of indanthrene RS powder are mixed and stirred with500 parts of monohydrate (1.838 specific gravity) cooled down to about 0C. or below. The yellowish-green magma thus obtained containing thesulfate of the indanthrene separated, is dissociated with ice-water,which should advantageously be done quickly, so that the dissociationoccurs before the minute sulfate crystals are transformed into coarsercrystals, the indanthrene-dyestuff is then filtered off and freed fromthe acid by washing.

Example II: 100 parts of indanthrene RS powder are mixed and stirredwith 500 parts of sulfuric acid of 66 B., (1.84 specific gravity), afterhaving stirred for a short time the yellowish-green sulfate whichseparates it is dissociated with ice-water; the further operation isperformed as indicated in Example I. If in the place of the indanthreneRS other brands, for instance the halogenated indanthrenes (indanthrenelC, etc.) are used and treated in the abovedescribed manner withsulfuric acid, either at a low temperature or at 40 C., there will alsoseparate sulfates, and after dissociating the pulpy magma in sulfuricacid with water, the indanthrene dyestuff is obtained in afinely-divided condition. \Vhen using slightly fuming acid it isadvantageous to work below 0 C.

Example III: 100 parts of indanthrene crude powder or, for instance.indanthrene RS are mixed and stirred with 700 parts of sulfuric acid of60 B. (1.84 specific gravity) cooled down to 0 C. The magma thusohtained becomes brownish-yellow with formation of indanthrene sulfate.After having gradually added about 60 parts of ice, the color of themagma turns green in consequence of the partial dissociation of theindanthrene sulfate this magma is then slightly heated and filtered off.The indanthrene-dyestuff remaining on the'filteris washed by treating itwith a small quantity of sulfuric acid of 60 B.. The impurities of theindanthrene, for instance the flavanthrene, remain dissolved in theyellowish-brown lye. It is advantageous to dissolve in the sulfuric acidto be used for the solution, small quantities (about 20 per cent. orless of indanthrene) of additional organic agents (for instance aromaticor other sulfonic acids, etc.) such as have been found, according to U.S. Patents Nos. 1,058,019, 1,057,880 and 1,057,887, to be suitable forthe transformation of indigo into finely-subdivided indigo; thus it isof advantage to add sodium benzylsulfanilate or the like. Suchadmixtures facilitate the separation of the indanthrene sulfate in avery finelydivided condition and thus the production of an extremelyfinely-divided dyestufi' which may also be used as a pigment dye.

Example IV: One part of indanthrene powder is introduced into 5 parts ofconcentrated sulfuric acid of 1.84 specific gravity and heated to about100 C. so as to give a solution. -This solution is allowed to cool,while stirring it, whereupon the sulfate separates as crystals which arefiltered off, Washed with a small quantity of sulfuric acid anddissociated by introducing them into icewater. The indanthrene thusobtained is crystalline and yields very pure tints.

Example V: 100 parts of indanthrene RS are ground in a ball-mill with1400 parts of sulfuric acid of 58 B. (1.67 specific graity) for abouttwo hours at 20 C. The magma which is at first thin-liquid soon becomesvery thick. To this blue magma 1400 parts of ice are added and theindanthrene dyestufl is filtered off. The indanthrene thus obtainedshows a very fine, pigment-likesubdivision.

Example VI: 100 parts of indanthrene in amorphous form. as obtainable bydis solving indanthrene in highly concentrated sulfuric acid (1.838specific gravity) and rapidly precipitating with water. or by blowingair in the cold solutions of indan threne in the rat or from the fusion,are mixed and stirred in the cold with1500 parts of sulfuric acid of 58lie. until the coarsely. amorphous i-lyestull lumps have become dividedinto very minute dycstuff-particles, which, when seen through amicroscope, ap pear to be even smaller than tubercle bacilli. Theoperation may even be carried out while gently heating, particularlywhen it is intended to obtain the indanthrene in a somewhat differentcondition. The resulting magma is washed with water to remove thesulfuric acid. The indanthrene dyestulf thus obtained is of an extremelyfine division and possesses an extraordinary power of yielding pigments,which is due to the fact that the individual crystalline particles ofthe new product are smaller than tubercle bacilli, which is not the casewith any of the indanthrene-dyestuffs hitherto manufactured orpreviously described in literature.

Example VII: 20 parts of dibromindanthrene (commercial indanthrene G0)are heated in the form of a paste with 300 grams of sulfuric acid of 60B. (1.71 specific gravity) for several hours to 8090 C. The coarselyamorphous lumps of the dyestuffpaste are thus transformed into smalluniform crystalline needles. There may be obtained extremelymicrocrystalline or more coarsely crystalline products according to thetemperature and the concentration of the acid used. For working up theresulting magma the acid is removed by washing with water and thedyestufi' is filtered off and made into a paste or evaporated into apowder.

Example VIII: 100 parts of indanthrene powder, either in a coarsecrystalline form, as obtained, for instance, by solution andcrystallization from concentrated sulfuric acid, or in an amorphousform, are mixed and stirred for some hours at 100120 C. with 1100 partsof sulfuric acid of 75 per cent. strength (1.67 specific gravity). Aftercooling, 100 parts of ice are added to the magma and the dyestuff isisolated by filtration. The finely-divided indanthrene dyestufi' thusobtained is in the form of fine uniform needles.

Example IX: 100 parts of indanthrene GC powder are mixed and stirred forone hour at 40 C. with 1000 arts of sulfuric acid of 60 B.; (1.71specific gravity) after adding 1000 parts of ice, the dyestulf isfiltered off. The indanthrene-dyestuff thus obtained consists of veryfine uniform crystals of a blue color and a pigment-like structure.

Example X: 100 parts of indanthrene powder crude, or RS powder, are wellmixed and stirred for one hour at 4050 1. with 1000 parts of sulfuricacid of 75 per cent. strength (1.71 specific gravity). The magma thusobtained is filtered off and washed by treating it with sulfuric acid.The dyestufl thus obtained is freed from the acid; it dyes pure tintsand gives very even prints, which proves its fine and uniform division.

Having now described our invention what we claim is:

1. The process of manufacturing finelydirided vat-dyestuffs of thedihydro-1.2.i2'.lanthraquinonazin (indanthrene) series, which consistsin treating said dyestuffs first with a quantity of a sulfuric acidinsufiicient to dissolve the indanthrene in the cold, and then withwater.

2. The process of manufacturing finelydivided vat dyestuffs of theindanthrene series, which consists in treating said dyestufis first withsulfuric acid of 66 B. to 481 B., i.e., 1.841 to 1.5 specific gravity.in quantity insufficient for the solution of the indanthrenes atordinary temperature, and then with water.

3. The process of manufacturing finelydivided vat-dyestuffs of theindanthrene series, which consists in transforming said dyestufl's froman amorphous to coarsely crystalline form into a finely crystalline formby heating it with sulfuric acid of about 1.67 to 1.6 specific gravityin quantity insufficient for the solution of the indanthrenes atordinary temperature and then treating the magma thus obtained withwater to remove the sulfuric acid.

4. The process of manufacturing finelydivided vat-dyestuffs of theindanthrene series, which consists in treating said dyestuffs with asulfuric acid in quantity sufficient for the solution of them atordinary temperature, filtering off and treating the residue with water.

5. The process of manufacturing finelydivided vat-dyestuffs of theindanthrene series, which consists in treating impure indanthrenedyestuffs with a highly concentrated sulfuric acid, and then dilutingwith a small quantity of water so that there remain the undissolvedindanthrene-dyestuffs and a sulfuric acid not below 1.5 spec. grav.which'is still ca able of dissolving the impurities, filteringo theresidue and treating the latter with water.

6. As new products, finely divided pigment dyes of the indanthreneseries showing the reactions of the dyestuffs of this class, but beingdistinguished from them by ex hibiting, when seen under the microscope,uniform, severally-visible particles, not exceeding about the size oftubercle bacilli and by possessing, when spread as a glue-water color(size paint-color), a greater covering power than the commercialindanthrenes and the product obtainable by treatment with glucose andalkali.

7. As a new product, finely divided dibromo-indanthrene in a newphysical form, showing the reactions of the dibromo-indanthrene, howeverbeing distinguished from the same by exhibiting, when seen under themicroscope, uniform severally-visible small crystalline particles.

In testimony whereof, We afiix our signatures in presence of twowitnesses.

ADOLF STEINDORFF. ROBERT WELDE.

Witnesses JEAN GRUND, Cam, GRUND.

It is hereby certified that in Letters Patent No. 1,145,934, grantedJuly 13, 1915,"

upon the application of Adolf Steindorfi' and Robert Welde, ofHochst-on-the- Main, Germany, for an improvement in- Finely-Divided VatDyeetufis and Processes of Making Same, errors appear in the printedspecification requiring correction as follows: Page 3, line 43 for theword greity read page 4, lines 27-28, claim 4 for the word suflicientread insufic'izmt; and that the said Letters Patentehould be read withthese corrections therein that the same may conform to the record ofthecese in the Patent Ofiice.

Signed and sealed this 12th day of October, A. D., 1915.

R. F. VVETEHEAD,

Acting C'mnmissioner of Patents.

[BEAL] Cl. 8l.

